Short of looking back over more than 1300 posts (sorry) is 'extension' of services through the Channel Tunnel (at either or both ends) intended to be in addition to or in substitution for existing services London to/from Paris/ Brussels? How much 'spare' capacity is there? Seems to me the principal constraint is Britain's requirements regarding customs/ immigration control, as witnessed by 'closures' at Ashford and Stratford and no link to HS2, or anything else in GB. Unless and until that changes I see only hot air.